Anwendung neuartiger Metalsiloxid-Katalysatoren für die ringöffnende Polymerisation zyklischer Monomeren zu bioabbaubaren und biokompatiblen Polymeren

该项目的目标是合成和利用新型金属硅氧化物作为催化剂，利用现成的廉价可再生资源生产可生物降解和生物相容性聚合物。具有医疗应用潜力的高性能材料（聚氧化物、聚酰胺）将通过环单体如丙交酯、环氧化物和morpholines的金属辅助开环聚合制成。在这方面，将设计、合成和研究新型通式[（R3SiO）“M]-OR催化剂，将无毒硅醇配体与廉价的生物相容性金属如Zn、Mg、Ca（或毒性较小的Y、La、Al）结合。这些化合物中的醇基（OR）是开环的引发剂，而吸电子的硅氧化物配体（R3SiO）则显著提高了金属的亲电性。我们认为，与相关系统相比，这将导致增强的活动和选择性。为了获得具有足够稳定性的活性金属硅氧化物，将通过用氯硅烷（R2SiC12）处理供体官能化有机锂试剂并随后水解制备具有悬垂供体基团并能配位到催化活性金属中心的新型立体负担硅醇。最后，将得到的硅烷醇用活性金属酰胺或醇氧化物处理，合成催化剂。

The objective of this project is to synthesize and utilize novel metal siloxides as catalysts for the production of biodegradable and biocompatible polymers from readily available, inexpensive renewable resources. Materials of high performance having a potential for medical application (polyoxogenates, polyamides) will be made by metal assisted ring opening polymerization of cyclic monomers such as lactides, epoxides and morpholines. In this regard, novel catalysts of the general formula [(R3SiO)"M]-OR, which combine non-toxic silanol ligands with inexpensive and biological compatible metals such as Zn, Mg, Ca (or less toxic Y, La, Al) will be designed, synthesized and studied. Whereas the alkoxide group (OR) in these compounds is an initiator for the ring opening, the electron withdrawing siloxide ligand (R3SiO) significantly increases the electrophilicity of the metal. We believe this should result in enhanced activities and selectivities in comparison to related systems. To obtain active metal siloxides of sufficient stability, novel sterically encumbered silanols with pendant donor groups that can coordinate to the catalytically active metal center will be prepared by treatment of donor functionalized organolithium reagents with chlorosilanes (R2SiC12) and subsequent hydrolysis. Finally, the catalysts will be synthesized by treatment of the obtained silanols with reactive metal amides or alkoxides.